Abstract
PurposeTo characterize human parafoveal blood flow using adaptive optics scanning laser ophthalmoscopy (AO-SLO).MethodsIn 5 normal subjects, erythrocyte aggregate distributions were analyzed on 3 different days. Erythrocyte aggregates were described as a “dark tail” in AO-SLO. The characteristics of the pathways with dark tail flow in the parafovea were measured. Additionally, the tendency for dark tail flow before and after bifurcations was analyzed to study the blood flow in detail.ResultsAverage velocity in parent vessels with dark tail flow was 1.30±0.27 mm/s. Average velocity in daughter vessels with dark tail flow was 1.12±0.25 mm/s, and the average velocity of plasma gaps in daughter vessels without dark tail flow was 0.64±0.11 mm/s. Downstream from the bifurcations, the velocity in vessels with dark tail flow was higher than that in those without it (p<0.001), and the branching angles of vessels with dark tail flow were smaller than those of vessels without it (p<0.001).ConclusionsImages from the AO-SLO noninvasively revealed pathways with and without dark tail flow in the human parafovea. Pathways with dark tail flow in the daughter vessels generally had faster flow and smaller bifurcation angles than daughter vessels without dark tail flow. Thus, AO-SLO is an instructive tool for analyzing retinal microcirculatory hemodynamics.
Highlights
Ophthalmoscopy is a standard procedure in every routine eye examination and is useful in detecting retinal changes caused directly by eye disease and those secondary to systemic disease
We described the ‘‘dark tail,’’ which we interpreted as a region darker than the vessel shadow, that may correspond to aggregated erythrocytes upstream of leukocytes
The eyes of all subjects were dilated before adaptive optics scanning laser ophthalmoscopy (AO-scanning laser ophthalmoscope (SLO)) image acquisition with 1 drop each of tropicamide (0.5%) and phenylephrine hydrochloride (0.5%)
Summary
Ophthalmoscopy is a standard procedure in every routine eye examination and is useful in detecting retinal changes caused directly by eye disease and those secondary to systemic disease. This includes retinal blood vessel changes resulting from high blood pressure [1,2,3], arteriosclerosis [4], and diabetes mellitus. Fluorescein angiography (FA) has long been the prevalent technique and the gold standard for evaluating retinal circulation, even with the potential side effects of fluorescein and the discomfort associated with the procedure These drawbacks may prevent normal subjects and patients with early disease from undergoing angiography. Other tools that do not rely on an angiographic agent for measuring retinal blood flow have been developed, including laser Doppler velocimetry [6], scanning laser Doppler flowmetry [7], laser speckle flowmetry [8], and retinal functional imager. [9] improved optical coherence tomography (OCT) systems, such as the Doppler OCT [10], can be used to examine retinal hemodynamics without a contrast agent
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
